SPI

Overview

In the Hardware Driver Foundation (HDF), the Serial Peripheral Interface (SPI) uses the independent service mode for API adaptation. In this mode, each device independently publishes a device service to handle external access requests. After receiving an access request from an API, the device manager extracts the parameters in the request to call the internal method of the target device. In the independent service mode, the service management capabilities of the HDFDeviceManager can be directly used. However, you need to configure a device node for each device, which increases the memory usage.

Figure 1 Independent service mode

Available APIs

SpiCntlrMethod:

struct SpiCntlrMethod {
  int32_t (*GetCfg)(struct SpiCntlr *cntlr, struct SpiCfg *cfg);
  int32_t (*SetCfg)(struct SpiCntlr *cntlr, struct SpiCfg *cfg);
  int32_t (*Transfer)(struct SpiCntlr *cntlr, struct SpiMsg *msg, uint32_t count);
  int32_t (*Open)(struct SpiCntlr *cntlr);
  int32_t (*Close)(struct SpiCntlr *cntlr);
};

Table 1 Callbacks for the members in the SpiCntlrMethod structure

Callback

Input Parameter

Return Value

Description

Transfer

cntlr: structure pointer to the SPI controller at the core layer.

msg: structure pointer to the SPI message.

count: number of messages. The value is of the uint32_t type.

HDF_STATUS

Transfers messages.

SetCfg

cntlr: structure pointer to the SPI controller at the core layer.

cfg: structure pointer to the SPI attributes.

HDF_STATUS

Sets SPI controller attributes.

GetCfg

cntlr: structure pointer to the SPI controller at the core layer.

cfg: structure pointer to the SPI attributes.

HDF_STATUS

Obtains SPI controller attributes.

Open

cntlr: structure pointer to the SPI controller at the core layer.

HDF_STATUS

Enables the SPI.

Close

cntlr: structure pointer to the SPI controller at the core layer.

HDF_STATUS

Disables the SPI.

How to Develop

The SPI module adaptation involves the following steps:

  1. Instantiate the driver entry.

    • Instantiate the HdfDriverEntry structure.
    • Call HDF_INIT to register the HdfDriverEntry instance with the HDF.

  2. Configure attribute files.

    • Add the deviceNode information to the device_info.hcs file.
    • (Optional) Add the spi_config.hcs file.

  3. Instantiate the SPI controller object.

    • Initialize SpiCntlr.

    • Instantiate SpiCntlrMethod in the SpiCntlr object.

      NOTE

      For details, see Available APIs.

  4. Debug the driver.

    • (Optional) For new drivers, verify the basic functions, such as the SPI control status and response to interrupts.

Development Example

The following uses spi_hi35xx.c as an example to present the contents that need to be provided by the vendor to implement device functions.

  1. Instantiate the driver entry. The driver entry must be a global variable of the HdfDriverEntry type (defined in hdf_device_desc.h), and the value of moduleName must be the same as that in device_info.hcs. In the HDF, the start address of each HdfDriverEntry object of all loaded drivers is collected to form a segment address space similar to an array for the upper layer to invoke.

    Generally, HDF calls the Bind function and then the Init function to load a driver. If Init fails to be called, HDF calls Release to release driver resources and exit.

    • SPI driver entry reference

      struct HdfDriverEntry g_hdfSpiDevice = {
    .moduleVersion = 1,
    .moduleName = "HDF_PLATFORM_SPI",// (Mandatory) The value must be the same as that of moduleName in the .hcs file.
        .Bind = HdfSpiDeviceBind,   // See the Bind function.
 .Init = HdfSpiDeviceInit, // See the Init function.
     .Release = HdfSpiDeviceRelease,  //See the Release function.
};
// Call HDF_INIT to register the driver entry with the HDF.
HDF_INIT(g_hdfSpiDevice);

  2. Add the deviceNode information to the device_info.hcs file and configure the device attributes in the spi_config.hcs file. The deviceNode information is related to registration of the driver entry. The device attribute values are closely related to the default values or value ranges of the SpiCntlr members at the core layer.

    In this example, there is only one SPI controller. If there are multiple SPI controllers, you need to add the deviceNode information to the device_info file and add the corresponding device attributes to the spi_config file.

    • device_info.hcs configuration reference

      root {
device_info {
    match_attr = "hdf_manager";
    platform :: host {
    hostName = "platform_host";
    priority = 50;
    device_spi :: device {// Configure an HDF device node for each SPI controller.
        device0 :: deviceNode {
        policy = 1;
        priority = 60;
        permission = 0644;
        moduleName = "HDF_PLATFORM_SPI";
        serviceName = "HDF_PLATFORM_SPI_0";
        deviceMatchAttr = "hisilicon_hi35xx_spi_0";
        }
        device1 :: deviceNode {
        policy = 1;
        priority = 60;
        permission = 0644;
        moduleName = "HDF_PLATFORM_SPI"; // (Mandatory) Driver name, which must be the same as that of moduleName in the driver entry structure.
           serviceName = "HDF_PLATFORM_SPI_1"; // (Mandatory) Unique name of the service published by the driver
        deviceMatchAttr = "hisilicon_hi35xx_spi_1";// The value must be the same as that of match_attr in the .hcs file.
        }
        ...
    }
    }
}
}

    • spi_config.hcs configuration reference

      root {
platform {
    spi_config {// Configure private data for each SPI controller.
      template spi_controller {// Template configuration. In the template, you can configure the common parameters shared by service nodes.
        serviceName = "";
        match_attr = "";
        transferMode = 0; // Data transfer mode, which can be interrupt transfer (0), flow control transfer (1), or DMA transfer (2).
        busNum = 0; // Bus number
        clkRate = 100000000;
        bitsPerWord = 8; // Bit width of the data transferred
        mode = 19; // SPI data input/output mode
        maxSpeedHz = 0; // Maximum clock frequency
        minSpeedHz = 0;  // Minimum clock frequency
        speed = 2000000; // Current message transfer speed
        fifoSize = 256; // FIFO size
        numCs = 1; // Chip select (CS) number
        regBase = 0x120c0000; // Used for address mapping.
        irqNum = 100; // Interruption number
        REG_CRG_SPI = 0x120100e4;       // CRG_REG_BASE(0x12010000) + 0x0e4
        CRG_SPI_CKEN = 0;
        CRG_SPI_RST = 0;
        REG_MISC_CTRL_SPI = 0x12030024; // MISC_REG_BASE(0x12030000) + 0x24
        MISC_CTRL_SPI_CS = 0;
        MISC_CTRL_SPI_CS_SHIFT = 0;
    }      
    controller_0x120c0000 :: spi_controller {
        busNum = 0; // (Mandatory) Bus number
        CRG_SPI_CKEN = 0x10000;    // (0x1 << 16) 0:close clk, 1:open clk 
        CRG_SPI_RST = 0x1;         // (0x1 << 0) 0:cancel reset, 1:reset 
          match_attr = "hisilicon_hi35xx_spi_0";// (Mandatory) The value must be the same as that of deviceMatchAttr in device_info.hcs.
    }      
    controller_0x120c1000 :: spi_controller {
        busNum = 1;
        CRG_SPI_CKEN = 0x20000;    // (0x1 << 17) 0:close clk, 1:open clk
        CRG_SPI_RST = 0x2;         // (0x1 << 1) 0:cancel reset, 1:reset 
        match_attr = "hisilicon_hi35xx_spi_1"; 
        regBase = 0x120c1000; // (Mandatory) Used for address mapping.
           irqNum = 101; // (Mandatory) Interrupt number
    }
    ...
    //(Optional) Add nodes to the device_info.hcs file as required.
    }
}
}

  3. Initialize the SpiCntlr object at the core layer, including initializing the vendor custom structure (transferring parameters and data), instantiating SpiCntlrMethod (used to call underlying functions of the driver) in SpiCntlr, and implementing the HdfDriverEntry member functions (Bind, Init, and Release).

    • Custom structure reference

      To the driver, the custom structure carries parameters and data. The values in the spi_config.hcs file are read by HDF, and the structure members are initialized through DeviceResourceIface. Some important values, such as the device number and bus number, are also passed to the object at the core layer.

      struct Pl022 {// Corresponds to parameters in .hcs.
    struct SpiCntlr *cntlr;
    struct DListHead deviceList;
    struct OsalSem sem;
    volatile unsigned char *phyBase;
    volatile unsigned char *regBase;
    uint32_t irqNum;
    uint32_t busNum;
    uint32_t numCs;
    uint32_t curCs;
    uint32_t speed;
    uint32_t fifoSize;
    uint32_t clkRate;
    uint32_t maxSpeedHz;
    uint32_t minSpeedHz;
    uint32_t regCrg;
    uint32_t clkEnBit;
    uint32_t clkRstBit;
    uint32_t regMiscCtrl;
    uint32_t miscCtrlCsShift;
    uint32_t miscCtrlCs;
    uint16_t mode;
    uint8_t bitsPerWord;
    uint8_t transferMode;
};

// SpiCntlr is the core layer controller structure. Its members are assigned with values by using the Init function.
struct SpiCntlr {
    struct IDeviceIoService service;
    struct HdfDeviceObject *device;
    uint32_t busNum;
    uint32_t numCs;
    uint32_t curCs;
    struct OsalMutex lock;
    struct SpiCntlrMethod *method;
    struct DListHead list;
    void *priv;
};

    • Instantiate the callback function structure SpiCntlrMethod in SpiCntlr. Other members are initialized by using the Init function.

      // Example in spi_hi35xx.c: instantiate the hook.
struct SpiCntlrMethod g_method = {
    .Transfer = Pl022Transfer,
    .SetCfg = Pl022SetCfg,
    .GetCfg = Pl022GetCfg,
    .Open = Pl022Open,
    .Close = Pl022Close,
};

    • Bind function

      Input parameters:

      HdfDeviceObject, an interface parameter exposed by the driver, contains the .hcs configuration file information.

      Return values:

      HDF_STATUS

      Function description:

      Associates the SpiCntlr object with HdfDeviceObject.

      static int32_t HdfSpiDeviceBind(struct HdfDeviceObject *device)
{
    ...
    return (SpiCntlrCreate(device) == NULL) ? HDF_FAILURE : HDF_SUCCESS;
}

struct SpiCntlr *SpiCntlrCreate(struct HdfDeviceObject *device)
{
    struct SpiCntlr *cntlr = NULL; // Create the SpiCntlr object of the core layer.
    ...
     cntlr = (struct SpiCntlr *)OsalMemCalloc(sizeof(*cntlr));// Allocate memory.
    ...
    cntlr->device = device; // Enable conversion between HdfDeviceObject and SpiCntlr.
     device->service = &(cntlr->service); // Enable conversion between HdfDeviceObject and SpiCntlr.
    (void)OsalMutexInit(&cntlr->lock); // Initialize the lock.
    DListHeadInit(&cntlr->list); // Add the corresponding node.
    cntlr->priv = NULL;
    return cntlr;
}

    • Init function

      Input parameters:

      HdfDeviceObject, an interface parameter exposed by the driver, contains the .hcs configuration file information.

      Return values:

      HDF_STATUS (The following table lists some status. For details about other status, see HDF_STATUS in the /drivers/framework/include/utils/hdf_base.h file.)

      Table 2 Input parameters and return values of the init function

      Status (Value)

      Description

      HDF_ERR_INVALID_OBJECT

      Invalid controller object

      HDF_ERR_MALLOC_FAIL

      Failed to allocate memory

      HDF_ERR_INVALID_PARAM

      Invalid parameter

      HDF_ERR_IO

      I/O error

      HDF_SUCCESS

      Initialization successful

      HDF_FAILURE

      Initialization failed

      Function description:

      Initializes the custom structure object and SpiCntlr.

      static int32_t HdfSpiDeviceInit(struct HdfDeviceObject *device)
{
int32_t ret;
struct SpiCntlr *cntlr = NULL;
...
    cntlr = SpiCntlrFromDevice(device);// Forcibly convert HdfDeviceObject to SpiCntlr by using service. For details about the value assignment, see the Bind function.
                                    //return (device == NULL) ? NULL : (struct SpiCntlr *)device->service;
...
ret = Pl022Init(cntlr, device);// (Mandatory) Instantiate the operation object customized by the vendor. The following is an example:
...
ret = Pl022Probe(cntlr->priv);
...
return ret;
}

static int32_t Pl022Init(struct SpiCntlr *cntlr, const struct HdfDeviceObject *device)
{
int32_t ret;
struct Pl022 *pl022 = NULL;
...
pl022 = (struct Pl022 *)OsalMemCalloc(sizeof(*pl022));// Apply for memory.
...
ret = SpiGetBaseCfgFromHcs(pl022, device->property); // Initialize busNum, numCs, speed, fifoSize, clkRate, mode, bitsPerWord, and transferMode.
...
ret = SpiGetRegCfgFromHcs(pl022, device->property); // Initialize regBase, phyBase, irqNum, regCrg, clkEnBit ,clkRstBit, regMiscCtrl, miscCtrlCs, and miscCtrlCsShift.
...
// Calculate the frequencies corresponding to the maximum and minimum speeds.
pl022->maxSpeedHz = (pl022->clkRate) / ((SCR_MIN + 1) * CPSDVSR_MIN);
pl022->minSpeedHz = (pl022->clkRate) / ((SCR_MAX + 1) * CPSDVSR_MAX);
DListHeadInit(&pl022->deviceList);// Initialize the DList linked list.
pl022->cntlr = cntlr;                // Enable conversion between Pl022 and SpiCntlr.
cntlr->priv = pl022;              // Enable conversion between Pl022 and SpiCntlr.
cntlr->busNum = pl022->busNum;    // Assign a value to busNum in SpiCntlr.
cntlr->method = &g_method;        // Connect to the SpiCntlrMethod instance.
...
ret = Pl022CreatAndInitDevice(pl022);
if (ret != 0) {
    Pl022Release(pl022);             // Release the Pl022 object if the initialization fails.
    return ret;
}
return 0;
}

    • Release function

      Input parameters:

      HdfDeviceObject, an interface parameter exposed by the driver, contains the .hcs configuration file information.

      Return values:

      –

      Function description:

      Releases the memory and deletes the controller. This function assigns a value to the Release API in the driver entry structure. When the HDF fails to call the Init function to initialize the driver, the Release function can be called to release driver resources. All forced conversion operations for obtaining the corresponding object can be successful only when the Init function has the corresponding value assignment operations.

      static void HdfSpiDeviceRelease(struct HdfDeviceObject *device)
{
    struct SpiCntlr *cntlr = NULL;
    ...
    cntlr = SpiCntlrFromDevice(device);// Forcibly convert HdfDeviceObject to SpiCntlr by using service. For details about the value assignment, see the Bind function.
                                    // return (device==NULL) ?NULL:(struct SpiCntlr *)device->service;
    ...
    if (cntlr->priv != NULL) {
        Pl022Remove((struct Pl022 *)cntlr->priv);// A forced conversion from SpiCntlr to Pl022 is involved. 
    }
    SpiCntlrDestroy(cntlr);                         // Release the Pl022 object.
}